The original differences in the rules of college and pro football reflected more concern for safety of college players.
1. College football always had the goal posts on the End Line. Pro football’s were on the Goal Line until 1974 when they were moved to the End Line. In prior days, pro players often used the Goal Post to block out defenders and this did add another element to game. However, the advent of specialty kickers and great defenses often made for a game of field goals which were much too easy.
2. In Pro football the defense was permitted to run with recovered fumbles. In college football, the offense took over at the spot of the recovery. This to me made pro game more exciting since it could suddenly change momentum. This was a big factor in my preference for the NFL.
3. If college players fell to the turf without contact from the opposing team, they were down at this point. Pro rules said players were not down unit some contact with the defense. This also made pro football more exciting. Nevertheless, the officials should flag a defender for using excessive force when merely touching a player could halt progress.